Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Within distinct housing spaced from panel circuit arrangement
Reexamination Certificate
2000-03-31
2001-11-27
Bradley, P. Austin (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Within distinct housing spaced from panel circuit arrangement
C439S092000, C439S723000, C411S107000
Reexamination Certificate
active
06322376
ABSTRACT:
FIELD OF THE INVENTION
This invention is in the field of stud bolt terminal connections in the power distribution box of automotive vehicles.
BACKGROUND OF THE INVENTION
An electrical junction block or power distribution box is used in automotive vehicles to streamline wiring by eliminating multi-branch wiring. The power distribution box consolidates branch circuits and fuses, typically by incorporating bus bars into a housing to connect vehicle battery power to various electrical components serving the vehicle. The power distribution box often uses a stud bolt to connect a vehicle battery terminal to the bus bar.
In one type of conventional power distribution box, the stud bolt is molded into the plastic cover of the power distribution box. The insert molding process for joining the stud bolt to the cover, and the additional material needed, increases the manufacturing cost of the power distribution box and prevents replacement of a broken or stripped stud bolt.
A second type of conventional power distribution box shown in
FIGS. 1 and 1A
provides the stud bolt
140
as a separate component for direct attachment to a portion
100
of the power distribution box. Stud bolt holding features are molded into the plastic material of the box rather than insert molding the bolt into the box. Specifically, an open-ended, three-sided slot
100
a
is formed in the plastic wall of power distribution box housing
100
, for example during the molding process. Slot
100
a
is sized to receive a square-headed stud bolt
140
in a radially sliding fit from the side of the housing. Sidewalls
100
b
and recessed platform
100
c
in slot
100
a
define the final resting place for stud bolt
140
, engaging it in a close friction fit on three sides of the square head to prevent rotation. A bus bar
120
is subsequently assembled in essentially permanent fashion to housing
100
, with a terminal portion
120
a
lying in slot
100
over bolt
140
. An aperture
120
b
in bus bar
120
fits over the threaded shank of the stud bolt to radially secure the stud bolt in position. A battery terminal
160
is subsequently secured to terminal end
120
a
of bus bar
120
by being placed over the protruding threaded shank of the stud bolt, followed by a nut (not shown) threaded onto the bolt shank and torqued to compress terminal
160
against bus bar
120
.
Although the radial sliding fit of stud bolt
140
in slot
100
a
is intended to permit the removal and replacement of stud bolts stripped or broken during assembly, the essentially permanent attachment of bus bar
120
to housing
100
makes this difficult.
Another disadvantage with the stud bolt holding arrangement of
FIGS. 1 and 1A
is that the plastic material of housing
100
directly absorbs any heat created by electrical arcing at the stud bolt. Arcing is often caused by insufficient torque on the nut securing the terminal to the stud bolt and bus bar. This can result in damage to the housing itself.
Insufficient torque generally results from the relatively low strength offered by slot
100
a
against the tendency of stud bolt
140
to rotate as the nut is applied.
SUMMARY OF THE INVENTION
The present invention is an apparatus and method for removably securing a stud bolt to the housing of a power distribution box, junction block, or similar device. In general, the invention is a separately-formed stud bolt holder adapted to be removably secured in a receptacle in the power distribution box (PDB) housing. The stud bolt holder is preferably made from material which is more heat-resistant than the material used for the PDB housing. However, the problem of potential arcing due to insufficient torque in the nut connection of a terminal to the stud bolt is greatly reduced by the greater ability of the stud bolt holder to withstand torque than stud bolt retention features molded directly into the PDB housing.
Because the stud bolt holder can withstand greater terminal-securing torque, the stud bolt threads are preferably sized to fracture before stripping to clearly indicate a failure to the person applying the nut.
In the event that the stud bolt is stripped or fractured during assembly, the stud bolt holder is configured to allow a replacement stud bolt to function as a disassembly tool. The removability of the stud bolt holder from the PDB housing makes it easier to get at a broken stud bolt for removal, and further allows the stud bolt holder itself to be replaced if damaged during assembly or by subsequent arcing at the terminal.
In carrying out this invention in an illustrative embodiment thereof, a stud bolt holder is sized to fit into an opening in a PDB housing under a bus bar contact plate. The holder is first inserted into the opening in the PDB housing from an underside of the housing. Latch projections in the opening mate with the exterior of the holder to removably secure the holder in the housing. The stud bolt is inserted shank first into the holder until the bolt head is locked in place by a set of resilient internal lock arms. At this point the shank extends from the holder through apertures in the bus bar and battery terminal. A nut is then threaded onto the shank and tightened with sufficient torque to secure the terminal against the bus bar in a reliable electrical connection.
If the stud bolt is stripped or fractured during assembly, another stud bolt can be inserted head first into the stud bolt holder until it abuts the head of the broken stud bolt. The internal lock arms in the holder are designed to be forced out of locking engagement with the broken stud bolt head by the replacement stud bolt head, such that a tap on the protruding shank of the broken stud bolt is sufficient to knock both the broken stud bolt and the replacement stud bolt out of the stud bolt holder.
These and other features and advantages of the invention will become apparent upon a further reading of the specification in light of the accompanying drawings.
REFERENCES:
patent: 2972367 (1961-02-01), Wootton
patent: 4056301 (1977-11-01), Norden
patent: 4500240 (1985-02-01), Moran et al.
patent: 5088940 (1992-02-01), Saito
patent: 5302070 (1994-04-01), Kameyama et al.
patent: 5423647 (1995-06-01), Suzuki
patent: 5795193 (1998-08-01), Yang
patent: 1500941 (1970-01-01), None
Bradley P. Austin
Harvey James
Yazaki North America
Young & Basile
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